rustc: Fix a number of stability lint holes

There are a number of holes that the stability lint did not previously cover,
including:

* Types
* Bounds on type parameters on functions and impls
* Where clauses
* Imports
* Patterns (structs and enums)

These holes have all been fixed by overriding the `visit_path` function on the
AST visitor instead of a few specialized cases. This change also necessitated a
few stability changes:

* The `collections::fmt` module is now stable (it was already supposed to be).
* The `thread_local::imp::Key` type is now stable (it was already supposed to
  be).
* The `std::rt::{begin_unwind, begin_unwind_fmt}` functions are now stable.
  These are required via the `panic!` macro.
* The `std::old_io::stdio::{println, println_args}` functions are now stable.
  These are required by the `print!` and `println!` macros.
* The `ops::{FnOnce, FnMut, Fn}` traits are now `#[stable]`. This is required to
  make bounds with these traits stable. Note that manual implementations of
  these traits are still gated by default, this stability only allows bounds
  such as `F: FnOnce()`.

Additionally, the compiler now has special logic to ignore its own generated
`__test` module for the `--test` harness in terms of stability.

Closes #8962
Closes #16360
Closes #20327

[breaking-change]

1 files changed, 4 insertions, 2 deletions

diff --git a/src/libstd/old_io/stdio.rs b/src/libstd/old_io/stdio.rs
index 70400619bea..0669af9cf9a 100644
--- a/src/libstd/old_io/stdio.rs
+++ b/src/libstd/old_io/stdio.rs
@@ -48,7 +48,7 @@ use str::StrExt;
 use string::String;
 use sys::{fs, tty};
 use sync::{Arc, Mutex, MutexGuard, Once, ONCE_INIT};
-use uint;
+use usize;
 use vec::Vec;
 
 // And so begins the tale of acquiring a uv handle to a stdio stream on all
@@ -383,12 +383,14 @@ pub fn println(s: &str) {
 
 /// Similar to `print`, but takes a `fmt::Arguments` structure to be compatible
 /// with the `format_args!` macro.
+#[stable(feature = "rust1", since = "1.0.0")]
 pub fn print_args(fmt: fmt::Arguments) {
     with_task_stdout(|io| write!(io, "{}", fmt))
 }
 
 /// Similar to `println`, but takes a `fmt::Arguments` structure to be
 /// compatible with the `format_args!` macro.
+#[stable(feature = "rust1", since = "1.0.0")]
 pub fn println_args(fmt: fmt::Arguments) {
     with_task_stdout(|io| writeln!(io, "{}", fmt))
 }
@@ -510,7 +512,7 @@ impl Writer for StdWriter {
         //
         // [1]: https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1232
         // [2]: http://www.mail-archive.com/log4net-dev@logging.apache.org/msg00661.html
-        let max_size = if cfg!(windows) {8192} else {uint::MAX};
+        let max_size = if cfg!(windows) {8192} else {usize::MAX};
         for chunk in buf.chunks(max_size) {
             try!(match self.inner {
                 TTY(ref mut tty) => tty.write(chunk),